Heavy Metals Speciation in Sediments and Effect on Water Quality in Nanhai Lake

Key words: 
• heavy metal /
• speciation /
• sediments /
• AVS /
• the Nanhai Lake /
• the Yellow River

Abstract: The speciation of Cu, Pb, Zn and Cd in sediments and the concentrations of Cu, Pb, Zn and Cd in overlying water, filtered water and pore water of the Nanhai Lake ,which is an abandoned channel of the Yellow River, are analyzed in this paper accompanied with the data of AVS (AcidVolatile Sulfide) and SEM (Simultaneous Extract Metals) in sediments. The data are compared with those of the Yellow River due to the same origin of sediments between the Nanhai Lake and the Yellow River. The investigation was made for the movement and transformation law of heavy metal in solidliquid two phase system. The results show that heavy metals concentration in residual fraction in Nanhai Lake is close to which in the Yellow River. Over 81.1% selected heavy metals are in suspended form in overlying water of the Nanhai Lake and the Yellow River. The high concentration of copper in Nanhai Lake's overly water is released from the sediments. The pore water functions as a pathway for heavy metal mobilization from sediments to water phase. The AVS is the controlling factor on heavy metal precipitation; whereas, the organic complexing agent is the key factor on mobilization of Cu from sediments to water.